Spray foam roofing in Denver: repair, recoating and recovers

How a spray foam roof works

An SPF roof is made on site. Two liquid components are mixed at the spray gun and applied to the roof, where they expand and cure within seconds into a rigid, closed-cell foam. The crew builds the foam up in passes to the thickness the job calls for. The result is a single continuous layer with no seams, laps or fastener holes.

Foam on its own can't stay exposed to the sun. Every SPF roof is finished with a protective elastomeric coating, usually acrylic, silicone or urethane, and sometimes with granules broadcast into the coating for traction and extra protection. The foam provides insulation, shape and waterproofing; the coating protects the foam.

That pairing gives SPF some useful strengths:

• Seamless and self-flashing. Foam is sprayed up curbs, parapets and around penetrations, which removes many of the joints where other roofs leak.
• Insulation built in. The foam layer adds continuous insulation over the whole roof, without the gaps between boards.
• Can fix ponding. The foam can be applied thicker in low areas to build slope toward drains.
• Lightweight. A foam roof weighs far less than a gravel-surfaced built-up roof, which can make it possible to recover rather than tear off.
• Renewable. When the coating wears, you recoat it. A maintained foam roof doesn't have to be torn off when its first coating is spent.

The recoat cycle, and why it matters

The single most important fact about an SPF roof is that the coating is a maintenance item. Coatings erode slowly under sun, weather and foot traffic. As long as there's enough coating left, the foam is protected. Once the coating wears through, UV attacks the foam surface, which turns brown and powdery and starts to erode.

Recoating on schedule resets the clock. The interval depends on the coating type, how thick it was applied, the roof's exposure and traffic, and how well it's been maintained. Manufacturer warranties on coatings are generally tied to the coating type and applied thickness, so a recoat can often be specified to carry a new warranty.

We match the recoat to what's already on the roof. Some coatings don't bond to others without the right primer, and a recoat that peels after one winter is a waste of money. Adhesion tests are part of how we scope a recoat.

UV at altitude

Denver's elevation means stronger ultraviolet exposure than most of the country, and Front Range roofs see a lot of clear, sunny days. Both shorten coating life. On an SPF roof, that shows up as chalking, thinning coating on the south-facing and highest areas, and early erosion around walk paths and rooftop equipment where traffic wears the surface.

That's why we measure coating thickness during inspections instead of judging it by eye. A coating that looks fine from the roof hatch can be thin enough that the foam is close to exposure. Catching it a season early is the difference between a routine recoat and foam repairs.

Hail and bird damage

Hail

Hail season along the Front Range runs from mid-April to mid-August. Hail leaves dents in SPF. The question after a storm isn't whether there are dents but whether the coating is broken. Small dents with intact coating are usually not a leak risk. Hail that fractures the coating or crushes the foam surface opens the roof to UV and water, and those impacts need to be sealed and recoated before they grow.

After a storm we look at impact size and density, test whether the coating is fractured, and photograph every roof section with the storm date for your records or your insurer. Granule-surfaced coatings and tougher base coats can improve hail resistance on a new installation or a recoat. Our after-a-hailstorm checklist walks through the first steps.

Birds

Birds peck at foam. Northern flickers, which are common along the Front Range, are known for drilling into foam and other soft building surfaces, and other birds pick at damaged spots. Their holes can go through the coating and well into the foam. Each one is small, but they let water in and they're easy to miss without a close inspection. We seal bird damage with compatible materials, and where birds keep returning, we'll talk through deterrents and harder surfacing.

Checking a foam roof for moisture

Closed-cell foam resists water well, but it isn't immune. Water can get in through unrepaired punctures, open bird holes, failed details at drains and curbs, or worn-through coating. It then spreads between the foam and the old roof or deck below, where it can cause the foam to lose its bond with the roof below. Before any recoat or repair, we check:

• An infrared moisture survey to map suspected wet areas
• Core samples to confirm what's underneath and measure foam and coating thickness
• Soft or spongy areas and blisters that may mean the foam has lost its bond to the roof below
• Drains, scuppers, curbs and roof edges, where water tends to get in
• Adhesion of the existing coating where a recoat is planned

Recoating over wet foam traps the water. Wet sections have to be cut out, dried and replaced with new foam first.

Repair and recoat, or replace?

Because foam is renewable, most aging SPF roofs are candidates for restoration. The survey decides how far the work needs to go:

1. Survey

   Infrared scan, cores, coating thickness and adhesion tests. You get a marked-up roof plan showing what's dry, what's wet and what's thin.

2. Repair

   Cut out and replace wet or damaged foam, seal hail fractures and bird holes, and rebuild failed details at drains, edges and penetrations.

3. Prepare

   Power-wash the roof, let it dry and prime where the coating chemistry calls for it. Preparation is most of what makes a recoat last.

4. Recoat

   Apply the specified coating to the thickness required for the warranty and life you want, with granules or extra thickness in walk paths and around equipment.

5. Document

   Thickness readings, photos and warranty paperwork, so the next recoat can be planned instead of discovered.

Full replacement makes sense when wet foam is widespread, the foam has lost its bond to the roof below across large areas, or the foam was left uncoated long enough to erode badly. In that case the old foam comes off and a new SPF or single-ply roof goes on. We'll show you the survey results behind any recommendation.

When SPF fits as a recover

SPF is often at its best going over an existing roof. Because it adheres directly to a prepared surface, fills irregularities and adds insulation, it can extend the life of a building without a full tear-off. It tends to fit well over:

• Built-up roofs that are dry, once loose gravel has been removed and the surface prepared.
• Metal buildings with low-slope panels, where foam fills the profile and seals every fastener and lap.
• Roofs that pond, where foam can be tapered to drain.
• Roofs with many penetrations, where self-flashing foam removes a lot of leak-prone detail work.

It's not a fit everywhere. A recover is only an option when the existing roof is dry and code allows another layer, and building codes limit how many roof layers you can have. Raising the roof surface also affects parapet, door threshold and flashing heights. And SPF is weather-sensitive: it needs a dry surface, suitable temperatures and calm enough wind to spray. On the Front Range, that means planning around spring storms, chinook winds and short winter days.

Spraying on occupied and mixed-use sites

Overspray is the main risk of an SPF job in a busy area. Foam and coating mist can drift onto cars, windows and neighboring buildings when the wind picks up. We manage it with wind monitoring and stop rules, screening, covered or relocated parking, protected rooftop units and air intakes, and clear notices to tenants or residents. On association and mixed-use properties, we coordinate parking and access with your manager, the same way we do for any HOA or multifamily project.

Maintaining a spray foam roof

A foam roof needs more regular attention than most systems because its coating is its protection. Twice-a-year visits through our S.M.a.R.T. program, plus a check after hail, should include clearing drains, checking for bird damage and punctures, measuring coating thickness in the most exposed areas and sealing small defects before they let water in. Every visit ends with a written report with photos, so you can budget the next recoat years ahead.

Spray foam roofing FAQs